It is well-known that a type of rotary stamping machine, for example that used in the manufacture of boxes from corrugated cardboard sheets based on passing a sheet of corrugated cardboard between two cylinders, is provided with a die-holder cylinder where the die and a counter-die cylinder are mounted and provided with shrouds that are usually made of plastic laminar material, such as polyurethane, where the blades for cutting the corrugated cardboard are sunken.
The shrouds usually become unevenly worn over time by repeated penetration of the die-blades, resulting in areas with a significantly smaller diameter and, therefore, areas of lesser penetration or lesser pressure of the blades, a fact that may cause problems during stamping operations so much that it can prevent cutting and/or cause problems related to splitting.
A first known solution to prevent this uneven wearing involves rectifying the surface of the blades regularly. However, this solution requires downtime in production and/or in turn causes accelerated wear of said shrouds.
Another solution known by the holder to reduce this drawback involves applying a slow axial movement (and of small range) of the counter-die cylinder such that the worn area of said counter-die cylinder is more evenly distributed and not centred on one particular area. Said solution fails to completely solve this problem because it produces grooves the size of the movement of the counter-die cylinder whose range is limited due to problems of space between beds (limited to approximately 50 mm).
Finally, shroud rotary systems spreading wear evenly across all shrouds are known and widely used in combination with the aforementioned solutions. The problem with rotation is the difficulty, hazards and time required to remove and secure the shrouds and to move the remaining shrouds.